A tank has an iconic shape and when it deviates from that it looks strange, despite the fact that many of these alternative forms are equally viable. They include designs that are based on steam tractors, tricycles and cannon and ones where ordinary tanks are adapted for different tasks such as mine clearing. In the latter case, the Progvev T is particularly weird, where the gun has been replaced by a reverse mounted Mig fighter jet engine, in order to clear mines by blasting them with an afterburn.